1. Field of the Invention
This invention relates in general to the field of transportation and more particularly to overhead guideway systems in which a payload is suspended from a motive unit traveling within the guideway channel and employing steerable wheels combined with electronic sensors and control for laterally positioning the motive unit within the channel.
2. Brief Description of the Prior Art
Transportation is one of the greatest problems in the world today. Traffic accidents kill 40,000 people each year in the USA alone and many more are severely injured. Many people waste several hours per day stuck in traffic that is constantly getting more and more congested. Automobiles are a major source of air pollution and consume prodigious amounts of fossil fuel. Roadways use vast amounts of valuable land while land for new roads is often impossible to come by, especially in urban areas where new roads are needed the most.
Over the years, attempts have been made to wean people from their cars onto mass transit systems such as light rail and bus systems. These have been ineffectual in reducing pollution and congestion in metropolitan areas. In spite of claims to the contrary by proponents, light rail systems have a capacity that is only a fraction of that of a freeway and yet are outrageously expensive in terms of cost per passenger served. They also suffer from the "can't get there from here" syndrome; most people have to use their automobiles to get from their homes to a train stop and then use buses to get anywhere near their destination.
Mass transit systems are inherently inefficient. They require the entire vehicle and all of its passengers to constantly start and stop to service just a few passengers per stop. They also force people into a schedule that is not their own and often require multiple transfers sometimes under unpleasant weather conditions. They also subject passengers to conditions of overcrowding and discomfort.
Those who push for mass transit fail to recognize the fact that people like their cars. They like the privacy, mobility, freedom and the personal nature of private automobiles and are willing to put up with the concomitant congestion and frustration. The private automobile and road system, for all its problems, actually works well because people are able, at a moment's notice, to drive in as much comfort and style as they can afford directly to any place they desire. Until such time as a transportation system is in effect that provides direct door-to-door service, people will continue to use their own cars and no amount of lecturing and cajoling will change this situation. Rather than trying to force people into a situation they do not want, we need to provide a solution to the simple problem of getting from point A to point B that takes into account the desire of people for privacy and personalized service.
Our current surface transportation system evolved over thousands of years starting with simple footpaths and is now quite sophisticated. However, all transportation systems based on surface roads or railways suffer from a number of basic flaws. They all use vast amounts of valuable land area that is often very hard to come by especially when additional capacity needs to be added in a metropolitan area. They are often paralyzed by snow and ice and are made dangerous by rain. They interfere with and endanger other surface traffic including pedestrians and bicycles. Surface street intersections cause vehicles to engage in a very inefficient pattern of stopping and starting. Cloverleaf interchanges allow continuous motion but require massive structures taking up an inordinate amount of land and can be used only rarely. It is time for a fresh approach to transportation that takes us off the surface road paradigm; one that can be the starting point for a brand-new evolution.
Any new approach must take into consideration the real requirements of an ideal transportation system and must not be just a Band-Aid solution that attempts to fix the symptoms rather than address the underlying issues.
An ideal transportation system should transport individuals in complete safety directly to their destination at a moment's notice and with minimal wasted time. It should combine high speed with vast capacity and immunity from congestion. It should minimize pollution and the use of fossil fuel while being quiet, convenient and enjoyable to use. It should minimize land use, should not interfere with pedestrians or other surface traffic and should not be an eyesore. It must be capable of operating under extreme weather conditions including ice, snow, fog, high winds, and drenching rain and must be designed to minimize loss of life in case of earthquake, landslide, tornadoes and even terrorist activity. It must be affordable and be capable of being implemented piece-wise while augmenting systems currently in use. It must not require huge investments in infrastructure before it can be used. It should not require that individuals own special vehicles but should encourage the use of electric cars.
Here are more details for selected issues:
Safety
The high level of accidents and of congestion on roadways stems from the fact that each vehicle is piloted by an individual human being with varying skill, mood and attention level. An ideal system will use automation and will not depend on the skill of humans for safety. Already, the National Automated Highway System Consortium has demonstrated computerized driving of specially equipped automobiles on a specially prepared California highway. However, the uncontrolled nature of surface roads along with the need for special vehicles poses major obstacles to a practical implementation of this experiment.
Time
An important measure of the quality of a transportation system is its ability to minimize the total transit time of an individual user. The total time includes both the time in transit and the time waiting to enter or exit the system. Time spent in the system where the user is able to comfortably read or perform work does not count as negatively as time where the user is jostled, cramped or is occupied with driving. Psychologically, time spent waiting for a vehicle to arrive counts much greater than time spent in the vehicle.
Capacity
The capacity of a ground transportation system depends on the number of lanes and the speed and spacing between vehicles at the most restricted choke point. Choke points include entrance and exit ramps and stations and interchanges. It does little good to have high-speed close spaced travel if vehicles have to either slow down or be widely spaced to enter or exit the travelway.
Pollution
The pollution emitted by today's automobiles stems from the fact that each vehicle has to carry its own energy supply. The only practical energy source that has the required capacity involves the burning of fossil fuel. Even if 100% clean fossil fuel burning automobiles were to be developed, they would still emit copious quantities of the greenhouse gas, carbon dioxide. Breakthroughs in completely non-polluting energy supplies have been right around the corner for the past 50 years and will probably continue to be right around the corner for the next 50 years. An ideal system would power vehicles directly from the travelway, eliminating the need for a massive on-board energy supply.
Congestion
Congestion is perhaps the greatest problem with the roadway system today, especially in the mind of the commuting public. People generally disregard safety and pollution issues but congestion causes daily frustration. The principal cause of congestion is demand exceeding capacity and is exacerbated by the individual driving habits of the public such as excessive and unwise lane changes, inappropriate speed and improper spacing.
Many transportation systems have been devised to replace or augment the current highway system. Prior attempts have all been either outrageously expensive or have contained a fatal design flaw that rendered them impractical. All have failed to properly address the above requirements for an ideal system. One of the most common pitfalls is the chicken and egg syndrome where expensive travelways must be built and each individual must own a special vehicle. No one would want to buy an expensive special vehicle without travelways and communities will not provide funding for expensive travelways if no one can use them.
Raised or overhead transportation systems have an advantage over our surface-based highway system in that they allow the ground under the travelway to be left natural or to be used for other purposes. They also eliminate interactions with pedestrians and other ground based traffic and allow free passage of wildlife in remote areas. The advantages of a raised monorail system have been known for a long time. The German Wuppertal monorail, which uses a passenger compartment that is suspended from the rail, has been in operation since 1901 and now carries around 50,000 passengers per day.
Overhead systems in which the payload rides above the track are top heavy and need massive (and thus expensive) guideways. Systems in which the payload is suspended from the guideway are inherently stable and can use much lighter and less expensive tracks.
There are several patents that recognize the advantage of an overhead guideway with suspended payload units.
Zimmerman, U.S. Pat. No. 3,118,392 proposes a system in which payload modules are suspended from motor modules which ride in an overhead inverted U shaped monorail track. Switching between tracks is accomplished by moving portions of the traction surface within junction sections.
Rypinski, U.S. Pat. No. 3,861,315 discloses a dual-mode transportation system in which a surface mode vehicle is transported with the aid of a motor module riding in an inverted U shaped overhead track.
Leibowitz, U.S. Pat. No. 4,841,871 discloses a raised monorail system that utilizes suspended passenger vehicles with aerodynamic lift while Halus, U.S. Pat. No. 5,653,174 discloses an aircraft that is powered and guided by a linear electromagnetic cable.
Petersen, U.S. Pat. No. 5,074,220 proposes an overhead monorail system in which payload cabins hang from a motorized carriage that rides inside an enclosed tube-like travelway. The carriage uses in-line wheels riding in a concave lower surface along with a guide wheel that travels in an upper concave surface. The payload is supported from the carriage by a flange that extends through a slot in the guideway. Although vehicles may turn onto a secondary guideway without any active components in the guideway, the turn mechanism utilizes guide rollers that contact cam surfaces on the sides of the guideway.
The following patents disclose switching mechanisms for suspended monorail systems.
Gerhard, U.S. Pat. No. 4,214,535 discloses a switch for a suspended railway vehicle with elastic wheels in which one wheel runs unsupported in a gap between pairs of rails while in the switch section. Ramps are used to compensate for compression of the wheel material. The scheme uses rollers that engage guiding surfaces in the sidewalls of the structure.
Hallett et al., U.S. Pat. No. 5,060,575 disclose a turn controller for a suspended track mounted vehicle. The system uses wide wheels that drive over the slot through which the payload hangs. However, guide rollers on the vehicle make contact with a guide vane on the track structure.
None of the above systems is capable of high-speed close-spaced travel. Many use cams or other mechanical contact between the vehicle and guideway for positioning and steering (especially in Y-junctions and the like.) Some use rounded wheels and rounded traction surfaces resulting in high levels of friction, wear and noise.
Accordingly, it is an object of this invention to provide an overhead transportation system that can operate at very high speeds with minimal contact between vehicle and guideway.
Another object of this invention is to provide a transportation system that can operate with minimal spacing between vehicles at full speed even when merging two vehicle streams into one or when splitting one stream into two.
A further object of this invention is to provide a transportation system that is mechanically simple with an inexpensive minimal sized guideway that utilizes no moving parts.
Yet another object of this invention is to provide a transportation system that can operate with a much higher degree of safety than a highway and in an energy-efficient and pollution free manner.
Still another object of this invention is to provide a transportation system that can transport people in the vehicles they already own, effectively converting fossil fuel vehicles into electric vehicles for the time they are on the system.
Other objects and advantages will become apparent from time to time throughout the specification and claims as hereinafter related.